By an open neighbourhood in ℂⁿ of an open subset Ω of ℝⁿ we mean an open subset Ω' of ℂⁿ such that ℝⁿ ∩ Ω' = Ω. A well known result of H. Grauert implies that any open subset of ℝⁿ admits a fundamental system of Stein open neighbourhoods in ℂⁿ. Another way to state this property is to say that each open subset of ℝⁿ is Stein. We shall prove a similar result in the subanalytic category: every subanalytic open subset in a paracompact real analytic manifold M admits a fundamental system of subanalytic...

Let $𝒥$ be a coherent ideal sheaf on a complex manifold $X$ with zero set $Z$, and let $G$ be a plurisubharmonic function such that $G=log\left|f\right|+𝒪\left(1\right)$ locally at $Z$, where $f$ is a tuple of holomorphic functions that defines $𝒥$. We give a meaning to the Monge-Ampère products ${\left(d{d}^{c}G\right)}^k$ for $k=0,1,2,...$, and prove that the Lelong numbers of the currents $M_k^{𝒥}:={\mathbf{1}}_Z{\left(d{d}^{c}G\right)}^k$ at $x$ coincide with the so-called Segre numbers of $J$ at $x$, introduced independently by Tworzewski, Gaffney-Gassler, and Achilles-Manaresi. More generally, we show that $M_k^{𝒥}$ satisfy a certain generalization...

In the 70’s, Nekhorochev proved that for an analytic nearly integrable Hamiltonian system, the action variables of the unperturbed Hamiltonian remain nearly constant over an exponentially long time with respect to the size of the perturbation, provided that the unperturbed Hamiltonian satisfies some generic transversality condition known as steepness. Using theorems of real subanalytic geometry, we derive a geometric criterion for steepness: a numerical function $h$ which is real analytic around a...

We prove that every holomorphic bijection of a quasi-projective algebraic set onto itself is a biholomorphism. This solves the problem posed in [CR].

We study coherent subsheaves 𝓓 of the holomorphic tangent sheaf of a complex manifold. A description of the corresponding 𝓓-stable ideals and their closed complex subspaces is sketched. Our study of non-holonomicity is based on the Noetherian property of coherent analytic sheaves. This is inspired by the paper [3] which is related with some problems of mechanics.

We construct a non-polynomially convex compact subset of the unit torus in ${ℂ}^2$ with polynomially convex hull containing no analytic structure.

Soit $\omega$ un germe en $0\in {\mathbf{C}}^n$ de 1-forme différentielle holomorphe, satisfaisant la condition d’intégrabilité $\omega \wedge d\omega =0$ et non dicritique, i.e. sur toute surface $Z$ non intégrale de $\omega$, on ne peut tracer, au voisinage de 0, qu’un nombre fini de germes de courbes analytiques $({\Gamma }_i,P_i)$, intégrales de $\omega$, avec $P_i\in Z\cap Sing\omega$. Alors $\omega$ possède un germe d’hypersurface analytique intégrale.

In this paper we prove the implicit function theorem for locally blow-analytic functions, and as an interesting application of using blow-analytic homeomorphisms, we describe a very easy way to resolve singularities of analytic curves.

On étudie les propriétés métriques des ensembles analytique réels $f=0$, avec $f\in 𝒪\left(\Omega \right)$, $𝒪\left(\Omega \right)$ algèbre analytique topologiquement noethérienne. Ainsi, on construit de larges classes d’algèbres $𝒪\left(\Omega \right)$ topologiquement noethériennes et vérifiant des conditions de Łojasiewicz globales d’un certain type. Comme application, on obtient des théorèmes de division de fonction ${𝒞}^{\infty }$ par des fonctions analytiques.

Soit $f(x,y)$ une fonction sous-analytique de ${\mathbf{R}}^n\times {\mathbf{R}}^m$ à valeurs dans ${\mathbf{R}}^{+}.$ Nous montrons que l’intégrale ${\int }_{{\mathbf{R}}^m}f(x,y)dy$ est une fonction log-analytique de $x.$ Nous en déduisons que le volume $k$-dimensionnel des éléments $Y_x$ d’une famille sous-analytique de sous-ensembles sous-analytiques globaux de l’espace euclidien ${\mathbf{R}}^m$ est une fonction log-analytique de $x.$ Un corollaire de ce résultat est le caractère log-analytique de la fonction densité $k$-dimensionnelle d’un sous-analytique global de dimension $k$ en tout point de sa fermeture topologique....

We give a relation between two theories of improper intersections, of Tworzewski and of Stückrad-Vogel, for the case of algebraic curves. Given two arbitrary quasiprojective curves V₁,V₂, the intersection cycle V₁ ∙ V₂ in the sense of Tworzewski turns out to be the rational part of the Vogel cycle v(V₁,V₂). We also give short proofs of two known effective formulae for the intersection cycle V₁ ∙ V₂ in terms of local parametrizations of the curves.

We consider the intersection multiplicity of analytic sets in the general situation. We prove that it is a regular separation exponent for complex analytic sets and so it estimates the Łojasiewicz exponent. We also give some geometric properties of proper projections of analytic sets.

We present a construction of an intersection product of arbitrary complex analytic cycles based on a pointwise defined intersection multiplicity.